Conventional wisdom has it that Mosaic was the first graphical web browser. Even though Mosaic - the basis for Netscape - certainly kickstarted the web revolution, it wasn't the first graphical web browser at all - that honour goes to Erwise, developed by four Finnish college students in 1991. It was more advanced than Mosaic, ran on the X Window System, but didn't catch on in the end. The four developers recently gave an interview detailing Erwise and its history.

Marc Andreessen was one of the original developers of Mosaic, and was funded by Jim Clark (SGI) to develop Mosaic into Netscape. In fact, Netscape Navigator 1.0 was little more than a rebranded NCSA Mosaic. Same code base.

And before Netscape Navigator hit 1.0, it was called 'Mosaic Netscape'. When I worked at an ISP way back when, we used to give customers a couple of floppies that included Trumpet Winsock for Win3.1 and the 0.9 version of Mosaic Netscape. You can even see a screenshot of it in the Wikipedia Netscape article: